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CosmoTheAstronaut t1_irvk88d wrote

Remember that colors really are in the eye of the beholder. The range of wavelengths and the number of visible colors vary from species to species. (And to a smaller degree: even from individual to individual.)

For example, what appears to be bright yellow to the human eye could be:

  • pure light at a wavelength of ~580nm (e.g. the yellow of the rainbow),
  • a mix of red at ~440nm and green at ~530nm (e.g. pure yellow on a computer screen),
  • any mix of the former two options.

Therefore, it was not the trees that evolved to show exactly these colors, it's rather humans that evolved to see these colors in a specific way. To another species, the color of trees in fall might look quite unspectacular.

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kilotesla t1_iryaebx wrote

The description of the origin of color from a physics and physiology perspective is helpful and accurate. I would urge caution about drawing firm conclusions from that. That does not mean that no plants evolved to reflect wavelengths that appear to animals as vivid colors. It seems to be the case for trees that the colors are a side effect of what they are really doing, but that is not a conclusion that applies to all plant colors and cannot be proven by the physics and physiology of color.

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